Stackable box

ABSTRACT

A stackable box has side walls and end walls upstanding from a base, the box being formed from a single sheet of material cut and creased to provide, between each end of each side wall and the adjacent end wall, a diagonally creased panel, the diagonal crease extending from the intersection between the base, the side wall and the end wall. The side walls are folded over on to the base and the portion of each diagonally creased panel between the diagonal and the end wall being secured to the end wall, whereby, when the side walls are pulled upwardly and outwardly from the base, the end walls are lifted. Each side wall has along the upper edge thereof a ledge panel extending inwardly of the box and parallel to the base and the end walls each have a flap along the upper edge thereof which is foldable over to extend parallel to the base and to co-operate with the ledge panels to hold the box in shape and provide a continuous ledge surface around the open upper face of the assembled box. Each of the side walls incorporates a secondary side panel with a fixing strip therealong secured to the base whereby to form double side walls.

FIELD OF THE INVENTION

This invention relates to a box suitable, for example, for the transportation of whole fish such as salmon.

BACKGROUND TO THE INVENTION

Whole fish such as salmon are typically transported to market packed in ice in a thermally-insulated box formed from expanded polystyrene or from expanded polystyrene beads. The boxes are intended to be single-use boxes that are disposed of when the fish reach the market. Such boxes are light in weight and relatively cheap to manufacture, but have a number of disadvantages. Firstly, polystyrene is difficult to recycle, both because of the nature of the plastics material and because of contamination by fish protein, which tends to be absorbed into the material, and so the material is of relatively low value; indeed there is typically a cost involved in its disposal after use. Secondly, because the material is relatively brittle, it is readily broken into small fragments, or into the individual beads from which the boxes are formed, thus presenting a pollution hazard during disposal. Thirdly, it is necessary to manufacture the boxes close to the source of the fish, because transporting the empty boxes would be costly. The capital and running costs of the necessary manufacturing plant add to the overall price of the fish.

Since the boxes contain melting ice, they must be capable of retaining strength when wet and, especially when transported by air freight, of resisting leakage of water. These requirements limit the choice of alternative materials that might be more readily recycled.

It has been proposed to use extruded fluted double-walled polypropylene sheet materials to form fish boxes. The sheet material can be cut and creased to form a blank which can be transported to the packing place and then readily assembled into a box for use. After use, the boxes can readily be flattened for transport to a recycling plant, for example in the vehicle that transported the fish. Since the material is smooth and impervious, it can be easily washed before being melted down to produce reusable plastics materials which can, for example be used to produce new sheet materials. The recycling of the boxes is therefore more economically viable than with conventional polystyrene fish boxes.

WO2017/089742 discloses a stackable box formed from a twin-wall olefin plastics sheet material as a cut and pre-creased blank that can be transported as a flat blank and then assembled at the point of use into an open box having a surrounding upper surface or ledge which can facilitate stacking of the boxes and ensure rigidity when loaded. While such boxes are economical to transport to the point of use as flat blanks and can be leak-proof and so especially suited to the carriage of fish in ice, the assembly at the point of use requires a relatively complex, and therefore costly, machine, and the capital investment required can make the use of such boxes uneconomic.

GB2125772A discloses an open-topped cardboard box or tray which can be pre-folded to a flat form which can be opened out for use by lifting the sides, causing the ends to lift with them because of an attached gusset. Assembly is then completed by folding over the end panels and inserting locking tabs into slots in the base of the box. Multiple gusset portions have to be folded into place in order to achieve assembly, requiring time and a certain amount of skill to complete. The cost of using such a box is therefore still unacceptably high, and the box cannot be made leak-proof for the carriage of fish in ice, for example.

JP2923557B discloses a box with a frame around its upper edge, assembled from a single sheet of board which can be pre-folded to a flat form in a similar manner to that of GB2125772A. If formed of suitable material it can be made leak-proof, but requires inset folded and glued panels to create the double walls at the sides reducing strength and the insulation value afforded by the double walls, which may be important where the boxes are used for fish packed in ice, for example.

SUMMARY OF THE INVENTION

The present invention provides a stackable box having side walls and end walls upstanding from a base, the box being formed from a single sheet of material cut and creased to provide, between each end of each side wall and the adjacent end wall a diagonally creased panel, the diagonal crease extending from the intersection between the base, the side wall and the end wall, the side walls being folded over on to the base and the portion of each diagonally creased panel between the diagonal and the end wall being secured to the end wall, whereby, when the side walls are pulled upwardly and outwardly from the base, the end walls are lifted, and wherein each side wall has along the upper edge thereof a ledge panel extending inwardly of the box and parallel to the base and the end walls each have a flap along the upper edge thereof which is foldable over to extend parallel to the base and to co-operate with the ledge panels to hold the box in shape and provide a continuous ledge surface around the open upper face of the assembled box. Each of the side walls incorporates a secondary side panel with a fixing strip therealong secured to the base whereby to form double side walls.

The portions of the diagonally creased panels secured to the end wall are preferably secured by adhesive, as are the fixing strips, where used.

The flaps on the end walls may each be provided with an additional outer flap which can be folded under and into engagement with the ledge panels. Alternatively, the flaps may be secured using welding or adhesive.

The sheet material is preferably a plastics sheet material, such as a twin wall olefin plastics sheet material, and more preferably the twin wall plastics material is formed with internal webs or flutes between the twin walls extending vertically in the side walls of the box.

The box of the invention is transportable as a flat blank, thereby minimising the cost of transport of the empty boxes to the packing plant, but are straightforward to erect into a usable box, by hand or using simple, and therefore low cost, machinery.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings, which illustrate exemplary embodiments of the invention:

FIG. 1 is a perspective view of a cut and creased blank according to a first embodiment before forming into a box;

FIGS. 2 to 7 are corresponding views to FIG. 1 illustrating the successive stages in forming the box from the blank;

FIG. 8 is a perspective view of a cut and creased blank according to a second embodiment before forming into a box; and

FIGS. 9 to 13 are corresponding views to FIG. 8 illustrating the successive stages in forming the box from the blank.

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENT

Referring first to FIGS. 1 to 7, a sheet of twin-walled fluted polypropylene is cut and creased, for example by pressing the sheet on to a first tool having a predetermined pattern of knives and heated creasing bars upstanding therefrom, thereby forming a box blank 1 as shown in FIG. 1. In the Figure, the cut edges are represented by solid lines, while the creases are represented by broken lines. The heated creasing bars serve to provide permanently indented lines along which the sheet can be folded to erect the box. It will be appreciated that while heated creasing bars will be suitable for forming creases in thermoplastic sheet materials, other materials may require different configurations for forming creases, for example knives to form scored lines in the material.

The blank 1 consists of a rectangular base panel 2 having along two opposed longer edges rectangular side panels 3 and 4 which can be folded up at right angles to the base panel. Each side panel 3 and 4 has along its outer edge a connecting web 8, 5 leading to a secondary side panel 7, 6. The connecting webs 8, 5 are each dimensioned to form a narrow ledge along the top edge of the respective side panel 3, 4 when the box is assembled. Each secondary side panel 7, 6 has along its outer edge a fixing strip 10, 9 respectively. The base panel also has rectangular end panels 11 and 14 along the opposed shorter sides thereof, each end panel being provided with a pair of joined flaps 12, 13 and 15, 16 respectively along the outer edge thereof. Each side panel 3, 4 is joined to each end panel 11 and 14 through a respective corner panel 17, 18, 19 and 20, each of which is of generally square shape, but with a rounded outer corner, and is provided with a diagonal reverse crease extending from the corner of the base panel 2 outwardly.

Referring to FIG. 2, the box blank is first formed in the factory by folding inwards the panels 7 and 10 on to side panel 3, and the panels 6 and 9 on to side panel 4. Glue is then applied along the fixing strips 9 and 10 and the diagonally-divided portions of the corner panels 17-20 that are adjacent to the end panels 11 and 14. It will be seen that the glue application can be carried out as a linear operation as the blank is moved in a lengthwise direction. Additional glue may need to be applied to the diagonally-divided portions outwardly of the first line of glue to ensure adequate adhesion.

The side panels are then folded over again so that the secondary panels 6 and 7 and the fixing strips 9 and 10 are brought into facing contact with the base panel 2. It will be seen that the glue on the fixing strips 9 and 10 will contact the base panel 2, while the glue on the diagonally-divided portions of the corner panels 17-20 will be brought into contact with the end panels 11 and 14 respectively. This stage is illustrated in FIG. 3. The blank will then be passed through a press while the glue cures. The glued blank can then be transported in flat form, minimising shipping costs.

FIGS. 4 to 7 show the successive stages of erection of the box at the point of use. This can be done manually, although it would be possible to effect machine assembly as well. Starting with the blank as illustrated in FIG. 3, the composite side panels 4-6 and 3, 8, 7 are pulled away from the base panel 2 so as to rotate to an upright position. This lifts the end panels 11 and 14 as the corner panels 17-20 fold along the diagonal lines. FIG. 4 illustrates the commencement of this action and FIG. 5 illustrates the fully lifted side and end panels. In this configuration, the side panels and secondary side panels now form double walls, with the fixing strips 9 and 10 anchoring to the base panel 2 and serving the hold the secondary panels 6 and 7 parallel to the respective side panels 4 and 3 with the connecting webs 8, 5 forming a ledge parallel to the base panel 2 along each side panel. The joined flaps 12, 13 and 15, 16 are then folded over to bring the panels 12 and 15 to rest on the ledges 8 and 5 as shown in FIG. 6.

The outer flaps 13 and 16 are then folded into the box to engage the end panels 11 and 14. It will be seen from FIGS. 1 and 2 that the connecting webs are cut with tabs 21, the secondary side panels 6 and 7 being notched inwardly accordingly. When the flaps 13 and 16 are folded onto the box, they pass over the tabs 21 and engage the notches to lock them in place. The finished box, shown in FIG. 7 is thus provided with a ledge surrounding the opening, facilitating stacking of the boxes. For larger boxes, such as are used for transporting fish such as salmon, a lid may be used, extending over the opening and the side and end walls, both to close the box and to give additional strength for stacking.

In a modified form of the box of FIGS. 1 to 7, the outer flaps 13 and 16 can be omitted, the flaps 12 and 15 being welded to the ledges 5 and 8 at each side to hold the box in shape in a machine-erection step.

While the box of FIGS. 1 to 7 is particularly suitable for larger loads, such as whole salmon, the double side walls giving additional strength and rigidity, smaller boxes used for lighter loads, may omit the double side walls, as shown in FIGS. 8 to 13, in which the parts in common with the first embodiment bear the same reference numerals. The differences in the blank, shown in FIG. 8, are that the secondary side panels and fixing strips are omitted so that the connecting webs 8, 5 become relatively widened ledge pieces. Accordingly, the first factory manufacturing step is simply the gluing of the diagonally-divided portions of the corner panels 17-20, which is followed by folding in of the side panels 3 and 4 and pressing of the corner panels until the glue has set, as shown in FIG. 9. The blanks can then be transported flat to the point of use.

Assembly at the point of use follows the same sequence as with the first embodiment: lifting the sides brings the end panels inwards as shown in FIG. 10. The joined flaps 12, 13 and 15, 16 are then folded over so that the flaps 12 and 15 rest on the horizontally-extending ledge pieces 8, 5 (FIG. 12). Finally, the flaps 13 and 16 are folded under the flaps 12 and 15 respectively to lock the box in shape.

The smaller boxes may be provided with a simplified lid, as their inherent rigidity, and the fact that they will not be loaded as heavily, does not require a full lid. Thus, for example, a simple sheet of the same material as used in the construction of the box can be configured with simple side flaps engaging under the ledge pieces to hold it in place, or a sheet can be welded in place to the ledge pieces 5 and 8 and/or the flaps 12 and 15. The closure could, alternatively be a simple sheet of plastics film or foil welded or glued to the peripheral upper surfaces 5, 8, 12 and 15 of the box.

While the folded corner design means that the boxes are inherently leak-proof when formed of plastics materials, they can be provided with drainage holes if required. 

1. A stackable box having side walls and end walls upstanding from a base, the box being formed from a single sheet of material cut and creased to provide, between each end of each side wall and the adjacent end wall a diagonally creased panel, the diagonal crease extending from the intersection between the base, the side wall and the end wall, the side walls being folded over on to the base and the portion of each diagonally creased panel between the diagonal and the side wall being secured to the end wall, whereby, when the side walls are pulled upwardly and outwardly from the base, the end walls are lifted, and wherein each side wall has along the upper edge thereof a ledge panel extending inwardly of the box and parallel to the base and the end walls each have a flap along the upper edge thereof which is foldable over to extend parallel to the base and to co-operate with the ledge panels to hold the box in shape and provide a continuous ledge surface around the open upper face of the assembled box, and wherein each of the side walls incorporates a secondary side panel connected to the ledge panel by a crease with a fixing strip therealong connected to the secondary side panel by a crease and secured by adhesive to the base whereby the fixing strips serve to hold each side wall parallel to the associated secondary side wall. 2-3. (canceled)
 4. A stackable box according to claim 1, wherein the flaps on the end walls are each provided with an additional outer flap which can be folded under and into engagement with the ledge panels.
 5. The stackable box according to claim 1, wherein the flaps on the end wall are secured by welding or adhesive.
 6. The stackable box according to claim 1, wherein the sheet material is a plastics sheet material.
 7. The stackable box according to claim 6, wherein the plastics sheet material is a twin wall olefin plastics sheet material.
 8. The stackable box according to claim 7, wherein the twin wall plastics material is formed with internal webs or flutes between the twin walls extending vertically in the side walls of the box.
 9. A method of making flat transportable blank for a stackable box as defined in any preceding claim, comprising creating the cut and creased sheet material and folding each secondary side wall and associated fixing strip on to the corresponding side wall and ledge panel, applying adhesive to the fixing strip and the portions of the diagonally creased panels secured to the end wall, and folding the secondary side walls and the adhesive-coated fixing strips into contact with the base and the diagonally creased panels into contact with the end walls, whereby the fixing strips are adhered to the base and the portions of the diagonally creased panels secured to the end walls are adhered to the end walls. 